7mm Making a common crossing for 7mm or S7 (the easy way)

[Dog Star]

Some months back I wrote about the construction of a 7mm / S7 common crossing from first principles... which is another way of writing the "hard way". I say the "hard way" because the angle for that crossing was 1:8.25 and there is minimal trade support, in regard to jigs, for such odd-ball non-integer crossing angles. The relevant WT-topic is here.

This topic is about the construction of a similar piece of Switch & Crossing work using jigs from the S7 Group... this is the "easy way" to making your own crossings. This crossing is 1:8 (for a Left Hand turnout) and I use the appropriate vee filing jig and crossing assembly jig from the S7 Group Stores (see here for details on the range of jigs from the S7 Group).

The S7 Group Vee filing and Crossing assembly jigs can be used to produce crossings with left hand divergence and crossings with right hand divergence. As the head of bullhead rail is of a different section to the foot of that rail then the point rail for a LH lead is a mirror image of the point rail for a RH lead (similarly for the splice rail). The vee filing jig produces point and splice rails in either a LH form or a RH form; the point and splice rails need to be produced as a matching pair for making a vee with a LH point rail and a RH splice rail is possible and just wrong (a vee formed with a LH and a RH rail is going to have one rail with the "head" at the top and one rail with the "head" at the bottom of the vee). LH and RH rails are produced by placing the rail in the filing jig with the rail head in the correct position for the required divergence - this "placing" of rails is noted in the captions to the photos.

This photo shows a rail positioned to produce a LH splice rail, the rail head is to the bottom of the slot. I use permanent marker pen on the rail to show progress in creating the taper. I remove sufficient metal as to leave a web of approximately half the original thickness.


This photo shows the completed splice rail for a LH turnout.


A LH point rail is given initially a similar taper to a LH splice rail so rail head to the bottom of the slot. After creating the initial taper the rail is removed from the filing jig and the rail is bent, at the end of the taper, so that the taper is "moved" from one side of the rail to the other side. This photo shows a LH point rail after filing the initial taper and then bending the rail so the taper changes sides.


The point rail is then replaced in the vee filing jig with the rail head to the open side of the slot. The rail is then filed to produce a new taper where the end of the rail has a web thickness of circa 10 thou (the rail end forms the blunt nose of the crossing).


After the second taper has been created the point rail is ready for forming the notch which houses the splice rail. This photo shows the point rail after cutting the notch - the point rail is positioned in the groove such that the notch is cut immediately adjacent to the end of the taper. Use of permanent marker enables monitoring of progess when filing the rail.


This photo shows how the vee filing jig is used to hold the point and splice rail to check the fit of the joint.

The vee filing jig holds the rails at approximately 6mm above the base of the jig so I use some MDF offcuts to support the joint whilst soldering. I use 245 degree C solder for this joint to minimise the chance of the vee falling apart when soldering the wing rails (in the next step).


And the result... after soldering / washing and before cleaning off of the excess solder.


regards, Graham

[the next step in creating the common crossing is to form the wing rails and then place wing / vee in the crossing assembly jig... next time (well actually after I have found the 1:8 assembly jig, ho hum)]

 

[mickoo]

Very timely tutorial as just about to embark on trackwork myself.

 

[ZiderHead]

Do the jigs include the 1 in 20 cant of the rail? (assuming thats required at the crossing)

 

[Dog Star]

Do the jigs include the 1 in 20 cant of the rail? (assuming thats required at the crossing)

Unfortunately not. I have enough trouble in forming wing rails which are "true" in the vertical plane let alone trying to include inclination in such items. The inclusion of rail inclination into crossings was discussed here.

regards, Graham

 

[S-Club-7]

I have enough trouble in forming wing rails which are "true" in the vertical plane let alone trying to include inclination in such items.

The prototype has a radius, not a sharp bend, in the knuckle rail. For a 1 in 8 crossing you need a radius of 10ft 8ins.

To get it inclined just form the curve using rolling mills. Using the GW Models small 150mm rolls I find the correct inclination is given by having one end of the rolls "unscrewed" 2mm more (i.e. 2 complete turns of the adjustment screw) than the other end. Or 2mm less, doesn't really matter as it's the difference that's important.

Process goes something like this: gently adjust BOTH ends so the rollers are touching i.e. parallel, then unscrew one end by 2mm. Now unscrew both ends the same amount (by counting turns of the screws) to feed the straight bit of the wing rail in before closing the rolls (each end by the same amount) until you've formed the required tapered/inclined radius of the correct angle.

Simples(-ish).

 

[ZiderHead]

Ahh thanks for the linky, with all the sharp minds round here I'm not at all surprised it has been discussed before

The rail twisting after construction sounds like fun

 

[ZiderHead]

To get it inclined just form the curve using rolling mills. etc.

now this is cunning

 

[Dog Star]

To get it inclined just form the curve using rolling mills. Using the GW Models small 150mm rolls I find the correct inclination is given by having one end of the rolls "unscrewed" 2mm more (i.e. 2 complete turns of the adjustment screw) than the other end.

A far more scientific method than the tool which I used here (fourth photo down).

regards, Mad Barking

 

[P-J.S.]

That makes it look oh so simple... very easy to understand too. I imagine it could be done without those jigs, but it seems so sensible to use them.

Is it just one block of metal that forms the jig for filing, tapering and holding then?

 

[Dog Star]

The prototype has a radius, not a sharp bend, in the knuckle rail. For a 1 in 8 crossing you need a radius of 10ft 8ins.

Um, sharp bend? Not me mate. Indeed the LNWR pre-1900 S&C practice shows some crossings with a radius of around 20ft..

 

[Dog Star]

Is it just one block of metal that forms the jig for filing, tapering and holding then?

The vee filing jig is a piece of steel with slots on one side for filing the taper / holding the rails for soldering... and a groove on the reverse face for cutting the notch into the point rail.

"Making a common crossing the hard way" (link in OP) shows how I made a crossing of angle 1:8.25 without a machined assembly jig... I do not wish to try to make the vee without some form of mechanical aid.

If anyone feels inclined to write a piece on making a vee and constructing a crossing without jigs then I shall be interested to read about such exploits... in a separate topic please.

regards, Graham

 

[daifly]

David 'S7' Nicholson's crossing jig:
There's more than one way to make them!
Dave

 

[Dog Star]

I finished the last post with the soldered vee although the item needed cleaning to remove the excess solder. Now for the assembly of a common crossing.

The first photo is of the soldered vees after cleaning and blackening.


Each vee needs two wing rails... here is the raw material, rail cut overlength to ease forming of the bends and to allow for adjusting the overall length of the crossing to fit the timber placing.


The three pieces of a common crossing with the wing rails formed to shape. The radius at the knuckle is a scale 21' (from LNWR drawing) with the flare set from the same drawings - the resulting shape of the wing rail is different to the typical turnout template and the formed rail does not fit the assembly jig.


I have modified the jig to accomodate the wing rails as formed rather than change the shape of the wing rails. This jig has suffered with loss of part of the spacer - not the first time that one of my jigs has fractured at the end of the spacer, probably a consequence of using paxolin for the jig. The black pen marks are for placing the brass strips (see later) and represent the positions of the turnout timbers under the crossing.


Assembly jig with a soldered vee - inserted upside-down as brass strips are going to be soldered to the foot of the rail.


The two wing rails are added - upside down with the foot of the rail to the top.


Soldering brass strips to steel rail - 188 degree solder and Safety-flux with a temperature-controlled iron set at 425 degrees (the hottest possible with the iron). Ugh, appearance is disgusting at this stage.


The assembled crossing needs easing out of the jig with great care... there are "ejector pin" holes in the base of the jig to help with this task. To much pressure at one end can (read - often does) lead to the crossing going out of shapeo and failure of the soldered joint at the crossing nose.


The top, correct, side of the crossing before cleaning and filing the brass strips to size. Prior to filing the brass the soldered crossing is dunked in a bosh for a few minutes and then scrubbed with a toothbrush to remove solder residue and any remaining flux.


The crossing placed in the appropriate position (trailing turnout in Up Main from the diamond in Down Main - see plan in original post of Hartley Hill). This shows how the brass strips are placed so as to sit on the timbers. Yes, yes, one strip is not central... not a worry as I shall blacken the rail / brass prior to fixing the crossing to the frmation and the chairs hide the strip.


regards, Graham

 

[Eastsidepilot]

Do the jigs include the 1 in 20 cant of the rail? (assuming thats required at the crossing)

The rails that form the vee ( point and splice rails) are vertical at the nose according to my "Standard Railway Equipment" info on permanent way for the LNER 1928
For example on a 1-7 or 7.5 " The point and splice rails to be vertical from the nose of the point rail to the heel of the splice. Frome the latter point each rail to be gradually canted towards the running side until the full inclination of 1 in 20 from the vertical is reached at a distance of 9 feet 6 inches back from the nose.
The wing rails to be canted towards the running side at an inclination of 1 in 20 from the vertical.
The check rails to be vertical."

The distance at which the inclination is reached varies depending on the angle of the crossing.

Col.

 

[S-Club-7]

The rails that form the vee ( point and splice rails) are vertical at the nose according to my "Standard Railway Equipment" info on permanent way for the LNER 1928
For example on a 1-7 or 7.5 " The point and splice rails to be vertical from the nose of the point rail to the heel of the splice. Frome the latter point each rail to be gradually canted towards the running side until the full inclination of 1 in 20 from the vertical is reached at a distance of 9 feet 6 inches back from the nose.
The wing rails to be canted towards the running side at an inclination of 1 in 20 from the vertical.
The check rails to be vertical."

The distance at which the inclination is reached varies depending on the angle of the crossing.

Col.

Funny that, my copy of the same book says exactly the same thing

But, if you look at the chair drawings a few pages further on you'll see that the B chair holds the "vee" rails vertically (page 36)A and the C chair holds them inclined (page 37). The B and C chairs are only spaced 2ft 6in apart which is nowhere near the 9ft 6in Col quoted from page 31

So what actually happened in practice?

 

[Dog Star]

I have referred to LNWR official drawings of S&C fittings in this thread and in the topic about Hartley Hill (see the Layouts Forum). Here is a sample of a crossing from a LNWR drawing which was prepared about 1905-1910.



Others have commented upon the radius of the wing rails through the knuckle, a dimension of circa 10' has been given previously - a separate LNWR drawing gives the knuckle radius for a 1:8 crossing as 21'0". I have made the crossings for Hartley Hill to as close a representation of this drawing as I am able and the visual difference between these crossings and others made to post-grouping drawings, especially in the area of the knuckle, is quite obvious.

regards, Graham

 

[Eastsidepilot]

Funny that, my copy of the same book says exactly the same thing

But, if you look at the chair drawings a few pages further on you'll see that the B chair holds the "vee" rails vertically (page 36)A and the C chair holds them inclined (page 37). The B and C chairs are only spaced 2ft 6in apart which is nowhere near the 9ft 6in Col quoted from page 31

So what actually happened in practice?

Perhaps they took an adz to the sleeper top face where the chair sits ? some more research needed even if only for interest sake.
In model form I don't think we need worry too much.........but please don't tell PJH or other wise.......

Col.